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Commit e390f9a9 authored by Josh Poimboeuf's avatar Josh Poimboeuf Committed by Ingo Molnar
Browse files

objtool, modules: Discard objtool annotation sections for modules 



The '__unreachable' and '__func_stack_frame_non_standard' sections are
only used at compile time.  They're discarded for vmlinux but they
should also be discarded for modules.

Since this is a recurring pattern, prefix the section names with
".discard.".  It's a nice convention and vmlinux.lds.h already discards
such sections.

Also remove the 'a' (allocatable) flag from the __unreachable section
since it doesn't make sense for a discarded section.

Suggested-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Cc: Jessica Yu <jeyu@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: d1091c7f ("objtool: Improve detection of BUG() and other dead ends")
Link: http://lkml.kernel.org/r/20170301180444.lhd53c5tibc4ns77@treble


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 55149d06

arch/x86/kernel/vmlinux.lds.S

+0 −2
Original line number Diff line number Diff line
@@ -345,8 +345,6 @@ SECTIONS 
	DISCARDS

	/DISCARD/ : {

		*(.eh_frame)

		*(__func_stack_frame_non_standard)

		*(__unreachable)

	}

}

include/linux/compiler-gcc.h

+1 −1
Original line number Diff line number Diff line
@@ -200,7 +200,7 @@ 
#ifdef CONFIG_STACK_VALIDATION

#define annotate_unreachable() ({					\

	asm("%c0:\t\n"							\

	    ".pushsection __unreachable, \"a\"\t\n"			\

	    ".pushsection .discard.unreachable\t\n"			\

	    ".long %c0b - .\t\n"					\

	    ".popsection\t\n" : : "i" (__LINE__));			\

})

include/linux/frame.h

+1 −1
Original line number Diff line number Diff line
@@ -11,7 +11,7 @@ 
 * For more information, see tools/objtool/Documentation/stack-validation.txt.

 */

#define STACK_FRAME_NON_STANDARD(func) \

	static void __used __section(__func_stack_frame_non_standard) \

	static void __used __section(.discard.func_stack_frame_non_standard) \

		*__func_stack_frame_non_standard_##func = func



#else /* !CONFIG_STACK_VALIDATION */

scripts/mod/modpost.c

+1 −0
Original line number Diff line number Diff line
@@ -854,6 +854,7 @@ static const char *const section_white_list[] = 
	".cmem*",			/* EZchip */

	".fmt_slot*",			/* EZchip */

	".gnu.lto*",

	".discard.*",

	NULL

};

scripts/module-common.lds

+4 −1
Original line number Diff line number Diff line
@@ -4,7 +4,10 @@ 
 * combine them automatically.

 */

SECTIONS {

	/DISCARD/ : { *(.discard) }

	/DISCARD/ : {

		*(.discard)

		*(.discard.*)

	}



	__ksymtab		0 : { *(SORT(___ksymtab+*)) }

	__ksymtab_gpl		0 : { *(SORT(___ksymtab_gpl+*)) }